Airflow on Good Ventilation

Airflow on Good Ventilation

Andrew Fram, Category Product Manager from Airflow Developments, looks at the importance of good ventilation in avoiding Toxic Home Syndrome and the solutions available to help maintain a healthy internal environment.

It is widely recognised that poor air quality in the home can have a detrimental impact on the health of its occupants. Over 15 million homes in the UK are at risk of Toxic Home Syndrome; a condition that occurs when inadequate ventilation fails to eliminate airborne allergens such as dust, pollen and mould spores, which can pollute the internal environment.

As such, effective ventilation is vital in maintaining a healthy home. For electricians undertaking regular house calls, it should be standard practice to check that each property has adequate ventilation and to suggest ways to improve ventilation levels if required.

What are the signs to look out for?Airflow-May-Long
As homes become more airtight, our sealed buildings can be more susceptible to damp, mould and condensation, especially in areas such as kitchens and bathrooms where we generate high levels of heat and moisture through cooking and bathing. A lack of effective ventilation can cause the building fabric to deteriorate and also may lead to respiratory problems for occupants.

Similarly, strong odours generated from cooking or smoking can be harmful if they are not effectively eliminated. The use of certain types of paint, cleaning products and building materials can also be damaging as they may contain harmful volatile organic compounds (VOCs) that can evaporate into the air. These can lead to headaches, dizziness and irritation of the eyes, nose and throat if they are allowed to remain.

Requirements for effective ventilation
Building Regulations Approved Document F and the accompanying Domestic Ventilation Compliance Guide set out the requirements for extract ventilation airflow rates in buildings. Guidelines on the recommended volume of air extraction for common ‘wet’ rooms in the home that typically drive ventilation requirements, are as follows:

  • Toilets: 6 l/sec (22 m3/hr)
  • Bathroom/shower rooms: 15 l/sec (54 m3/hr)
  • Kitchens adjacent to hob: 30 l/sec (108 m3/hr)
  • Kitchens without a cooker hood: 60 l/sec (216 m3/hr)
  • Utility rooms: 30 l/sec (108 m3/hr)

The guidance also highlights the importance of correct installation, commissioning and regular maintenance of ventilation systems so that optimum performance continues to be achieved once the system has been installed.

Choosing the right ventilation system
It is important to identify the most appropriate ventilation system for a homeowner’s requirements. There are a wide variety of systems on the market and these can generally be categorised into three key types.

Intermittent extractor fans are the most widely used ventilation option in bathrooms, kitchens or rooms without a window. They can be switched on manually or automatically via humidity and motion sensors, as and when required. The common types of intermittent extractor fan are:

  • Centrifugal and mixed flow fans – quiet, powerful fans that are suitable for working against pressure in ducted installations.
  • Axial fans – ideal for through-the-wall and window applications.

Mechanical ventilation with heat recovery (MVHR) systems offer a ‘whole house approach’ to ventilation. These units take stale air from inside the home and extract energy from it via a heat exchanger to recover heat that would normally be lost as part of the ventilation process. This energy is used to pre-warm clean fresh air that is continually being brought in from outside, which is then filtered and circulated around the home.


Using Electronically commutated (EC) motors, centrifugal fans consume up to 80% less energy than conventional AC motors, whilst offering significant noise reduction, variable speed control and remote monitoring options.

A de-centralised mechanical extract ventilation (dMEV) system can be a useful addition in highly insulated properties as it provides a quiet and unobtrusive ventilation option. Again, a continuously running ‘silent’ fan extracts moist air that causes condensation and mould, and replaces it with clean, fresh air that is circulated internally.

Where traditional ventilation systems work on an intermittent basis, dMEV units are in constant operation and come equipped with an ‘on-demand’ boost speed that kicks in with no human intervention required. The operating rate is set during installation according to the requirements of the room in which it is situated.

ErP compliance
The 2015 update to the Energy-related Products Directive (ErP) requires all fans and motors to comply with strict requirements in order to improve the efficiency of high energy-consuming building services.

The regulations are applicable to all 27 EU countries; all fans in the EU marketplace must be ErP compliant.

It is in the interests of all electricians to check that every home has an adequate ventilation system in place. Not only will this ensure a healthy environment to live and work in, but it will also enhance your professional reputation and potentially generate more business as a result of your recommendations.

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